61866 leans slightly Democratic by roughly 10 points: about 55% of voters vote Democratic and 45% Republican.
About 56% of adults in 61866 typically vote, below the U.S. average of about 62%. Among adults in 61866, ~31% vote Democratic, ~25% Republican, and ~44% don't vote. The map below shows estimated turnout by block group.
How 61866 compares
Among zip codes within 15 miles, 61866 leans more Democratic than 12 of 15 neighbors.
Politically, 61866 sits close to the rest of Illinois.
Politics vary noticeably by block within 61866. The south side runs the most Democratic (D+31) and the northwest side runs the most Republican (R+20), a spread of about 50 points.
Why 61866 leans the way it does
This analysis examined 14,881 data points per zip code to find what predicts political lean and turnout. The items below are a few correlations that stood out for 61866, not a ranked or complete list of what matters most.
Density combined with diversity predicts Democratic voting. Non-Hispanic white share in 61866 is about 54%, about 19 points below the U.S. average of 72%. A high never-married share predicts Democratic voting, and about 36% of adults in 61866 have never been married, above 80% of zip codes.
Preventive-care access and voter turnout
Places with limited routine preventive-care access tend to turn out at a lower rate; 61866, IL sits in the bottom quarter nationally on this measure. Dental visits do not drive turnout; the rate reflects income, insurance, and healthcare access, which line up with who votes.
Why turnout in 61866 looks the way it does
Areas with limited routine healthcare access turn out at lower rates. 61866 is in the bottom quarter nationally for routine-care measures such as insurance coverage, preventive screenings, and dental visits. Renters vote less often than owners, and about 45% of households in 61866 rent, compared to around 19% in nearby zip codes. High food insecurity lines up with lower turnout, and about 25% of adults in 61866 report food insecurity, above 88% of zip codes. Learn more about the findings and methodology on the political spectrum map.
Nearby Zip Codes
Zip Codes with Similar Populations
Sources and methodology
Precinct-level voting records used to fit the model come from Illinois State Board of Elections, distributed by the Voting and Election Science Team. Demographic inputs come from the U.S. Census Bureau (ACS 5-year estimates and the 2020 Decennial Census). Health and environmental inputs come from the CDC (PLACES and the Environmental Justice Index). Land cover comes from the USGS and EPA. Election-day and lead-up weather come from PRISM 4km daily grids and the NOAA Global Historical Climatology Network. Mail-voting and election-administration patterns come from the MIT Election Lab's Survey of the Performance of American Elections. Block-group crime detail comes from CrimeGrade. Internet data and modeling support provided by ISPreports.org.
Modeling and analysis by the BestNeighborhood data science team. Full methodology and findings: political spectrum map.
Methodology reviewed by the BestNeighborhood data team. Last updated May 2026.